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Check for page being resident when doing I/O with /dev/kmem and return

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EFAULT if it is not resident. This prevents the system from manufacturing
a zero-fill page for unused but allocated areas of the kernel's VM. This
should fix the "CMAP busy" panic that some people saw during system
startup.
This commit is contained in:
David Greenman 1995-09-15 23:49:23 +00:00
parent 6bd660b66b
commit 97e112628f
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=10812
2 changed files with 30 additions and 4 deletions
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17
sys/amd64/amd64/mem.c
View File

@ -38,7 +38,7 @@
*
* from: Utah $Hdr: mem.c 1.13 89/10/08$
* from: @(#)mem.c 7.2 (Berkeley) 5/9/91
* $Id: mem.c,v 1.11 1995/09/08 11:07:08 bde Exp $
* $Id: mem.c,v 1.12 1995/09/09 18:09:46 davidg Exp $
*/
/*
@ -163,13 +163,26 @@ mmrw(dev, uio, flags)
continue;
/* minor device 1 is kernel memory */
case 1:
case 1: {
vm_offset_t addr, eaddr;
c = iov->iov_len;
/*
* Make sure that all of the pages are currently resident so
* that we don't create any zero-fill pages.
*/
addr = trunc_page(uio->uio_offset);
eaddr = round_page(addr + c);
for (; addr < eaddr; addr += PAGE_SIZE)
if (pmap_extract(kernel_pmap, addr) == 0)
return EFAULT;
if (!kernacc((caddr_t)(int)uio->uio_offset, c,
uio->uio_rw == UIO_READ ? B_READ : B_WRITE))
return(EFAULT);
error = uiomove((caddr_t)(int)uio->uio_offset, (int)c, uio);
continue;
}
/* minor device 2 is EOF/RATHOLE */
case 2:

17
sys/i386/i386/mem.c
View File

@ -38,7 +38,7 @@
*
* from: Utah $Hdr: mem.c 1.13 89/10/08$
* from: @(#)mem.c 7.2 (Berkeley) 5/9/91
* $Id: mem.c,v 1.11 1995/09/08 11:07:08 bde Exp $
* $Id: mem.c,v 1.12 1995/09/09 18:09:46 davidg Exp $
*/
/*
@ -163,13 +163,26 @@ mmrw(dev, uio, flags)
continue;
/* minor device 1 is kernel memory */
case 1:
case 1: {
vm_offset_t addr, eaddr;
c = iov->iov_len;
/*
* Make sure that all of the pages are currently resident so
* that we don't create any zero-fill pages.
*/
addr = trunc_page(uio->uio_offset);
eaddr = round_page(addr + c);
for (; addr < eaddr; addr += PAGE_SIZE)
if (pmap_extract(kernel_pmap, addr) == 0)
return EFAULT;
if (!kernacc((caddr_t)(int)uio->uio_offset, c,
uio->uio_rw == UIO_READ ? B_READ : B_WRITE))
return(EFAULT);
error = uiomove((caddr_t)(int)uio->uio_offset, (int)c, uio);
continue;
}
/* minor device 2 is EOF/RATHOLE */
case 2: